A transmitting wireless node, such as an access point or a user device, having multi-user multiple-input-multiple-output (MU-MIMO) transmission capability is able to simultaneously transmit data (e.g., data frame) to multiple receiving wireless nodes via a set of spatial streams. In such MU-MIMO transmission, there may be one or more spatial streams for transmitting data to each of the receiving wireless nodes.
The transmitting wireless node performs rate adaptation by selecting a particular modulation coding scheme (MCS) and a particular number of spatial streams (Nss) used for transmitting data to each of the receiving wireless nodes via a MU-MIMO transmission. Typically, the selection of the particular MCS for a receiving wireless node is from among a set of available MCSs (e.g., MCS-1 to MCS-9). Similarly, the selection of the particular number of spatial streams for a receiving wireless node is from among a set of available numbers of spatial streams (e.g., Nss=1, 2, 3, or 4 (or other number of available spatial streams)).
Typically, the transmitting wireless node selects an MCS-Nss combination for transmitting data to a receiving wireless node based on the maximum expected data rates associated with the available set of MCSs and statistically-determined expected data error rates associated with the available MCS-Nss combinations, respectively. The transmitting wireless node typically selects a particular MCS-Nss combination in order to maximize the effective data rate (e.g., goodput) for transmitting data to each receiving wireless node via the MU-MIMO transmission. Accordingly, the disclosure herein relates to improvements in selecting the MCS-Nss combination for each receiving wireless node of an MU-MIMO transmission.